Metabolism of (+)-catechin and some of its C-6 and C-8 substituted derivatives in the isolated perfused pig liver.

The metabolism of (+)-catechin, 8-benzyl-(+)-catechin, 6-bromo-, 8-bromo- and 6,8-dibromo-(+)-catechin and 6- and 8-carboxymethyl-(+)-catechin by the isolated perfused pig liver resulted in the formation of the corresponding 3'-O-methyl derivatives. The position of O-methylation was determined by alkaline fusion. The bromo derivatives also underwent debromination. Unmetabolized material and metabolites were present as two glucuronides, a 3,4'-diglucuronide and a 3,5 (or 7)-diglucuronide, both in serum and bile. The position of conjugation was determined by methylation of free hydroxyl groups in the conjugates followed by unmasking of the conjugated hydroxyl groups by enzymic hydrolysis. Results indicate that substitution on the A-ring of (+)-catechin has little influence on the type of metabolites obtained.